Process and plant for the mechanical preparation of coals and minerals by washing in a plurality of chutes



Dec. 29, 1953 A. FRANCE 2,664,196

PROCESS AND PLANT FOR THE MECHANICAL PREPARATION OF COALS AND MINERALS BY WASHING IN A PLURALITY OF CHUTES Filed May 29. 1952 m xomwwzm fig mxwwzz M RU M '1 ATTORNEY Patented Dec. 29, 1953 PROCESS AND PLANT FOR THE MECHANI- CAL PREPARATION OF COALS AND MIN- ERALS BY WASHING IN A PLURALITY OF CHUTES Antoine France, deceased, late of Liege, Belgium, by Adolphe Detienne, executor, Liege, Belgium, assignor to Rhee-France Compagnie Internationale des Rheolaveurs A. France, societe anonyme, Liege, Belgium, a Belgian company Application May 29, 1952, Serial No. 290,676

1 Claim. 1

This is a continuation in part of application Serial No. 679,414 filed June 26, 1946, now abandoned.

This invention relates to a process and plant for the mechanical preparation of coals and minerals by washing in a plurality of chutes and has for its object to provide for the automatic regulation of the evacuation of dense materials, progressively and in a synchronized manner according to the variations in the nature or volume of the materials being treated.

This invention contemplates the washing of coal in plants consisting of one or more washing chutes placed above or next to one another, each chute being provided with a certain number of extractor devices or evacuators and having contingently in addition a re-washing circuit, the function of which is to bring back to the top or to a determined place in one of the chutes a certain proportion of the products under treatment.

In the art of mechanical preparation of coal and minerals, the plant is provided with one or more substantially horizontal chutes disposed one above the other. Each chute is preferably inclined slightly. The mineral to be processed is usually elevated by mechanical means such as buckets, elevators, conveyors or pumps, or fed from screens or storage bunkers to the head or upper end of a washing chute. The material can be fed dry and water added later, or it can be fed with entraining water.

The object of the process is to separate the light material from the dense materials. In the processing of coal, for example, it is desired to separate good coal having a low ash content from shale or mineral matter which accompanies the coal when it enters the plant. In this instance, the desirable coal will be the lighter material whereas the impurities will be more dense.

In the treatment of ore, on the other hand, the gangue is the lighter material whereas the concentrated desirable ore is more dense.

When the materials to be separated are fed to the chutes with a washing water, the more dense materials will tend to sink to the bottom of the chutes while the lighter materials move downwardly with the water to the discharge end of the chute where they are collected from suitable use or disposal. As indicated above, each chute is provided with a plurality of evacuators in the bottom thereof, which evacuators collect the dense material.

When a plurality of chutes are used, generally the separation in the uppermost chute is imperfect and a combination of light and dense materials is collected'in the evacuators. The materials thus collected, however, have a higher proportion of dense material than in the incoming feed. These materials are discharged, in a manner according to the invention, to the chute below where further separation takes place. This process is continued until the material in the evacuators in the lowermost chute comprises substantially only dense material.

The amount of the material fed into the chutes and the proportion of dense material will be variable and thus the depth or thickness of the deposit or the distance it rises up the inclined. slope will be variable. It is an object of the pres-- ent invention to keep the amount of alluviatiom deposit in the chutes fairly constant by proper regulation of the discharge of dense material. from the evacuators.

It is known that the variation in the size of the alluviation deposits in the washing chutes regulates the extraction of dense materials at a certain number of extractor devices in these same chutes.

The regulation of this extraction at the various chutes of a washing plant, when itdepends solely on consideration of the size of the alluvia deposits in each of the chutes taken separately, is not necessarily in close relation with the variations in the nature or volume of the dense materials included in the coal or ore to be treated.

This regulation may present manifest technical disadvantages such as insufficient qualitative and quantitative outputs of the washing plants and may necessitate the return of too large a proportion of the materials for re-washing.

It is an object of the present invention to secure automatically, at exact times and within limits which can be regulated at will, a variation of the outputs of certain number of evaouator devices in all the chutes of a washing plant according to the variations in the nature and the volume of the material to be treated indicated by the varying profile of the alluvation deposit in the first chute of the plant.

A further object of the present invention is to include certain corrective arrangements which also cause the extraction of dense materials at certain evacuator devices to depend on the size of the alluviation deposits in the chutes corresponding to these evacuators.

Additionally, an object of the present invention is automatically to control in a continuous manner'th'e' immediate dependence of the working of each of the chutes on the variation in the nature and volume of the dense materials included in the material to be treated.

To these and other ends the invention can employ special arrangements and an electrical installation including essentially electrical contacts such as electrodes, photo-electric cells, floats and the like for controlling the evacuators.

By way of example and without limitation, a. plant arranged according to the invention is described below with reference to the attached drawing.

Figure 1 is a diagrammatic side elevational view of a washing plant with three chutes.

Figure 2 is a side elevational view in section of an evacuator device.

Figure 3 shows an electric circuit arrangement for controlling the evacuators.

The dense material is sorted while being conveyed for purification by the washing water in said chutes and is taken up at intervals by extractor devices I of the kind shown in Figure 2.

Each extractor device consists of a body I of which the upper part ends in a channel 8 communicating with the bottom of the washing chute and the lower part by a discharge orifice 9.

The regulation of the degree of opening of the discharge or output orifice is effected by a stationary element It and a movable slide ll of trapezoidal section, the greater or lesser displacement of which forms a discharge orifice in the shape of a truncated cone having a section that is oval, circular or elongated within limits adjustable at will. This slide II is held in closed position by a tension spring 24, and is opened upon energization of electro-magnet Hi.

In Figure 1, electrical contacts are shown as a series of electrodes A1 to A8, electrically insulated from the chutes (as shown in Fig. 3) and fixed against one of the side walls of the latter at a certain height above the-bottom and at suitable distances from one another. The contacts are electrically connected to the electro-magnets I for causing their operation in a manner to be described below.

To close or merely to maintain closed the electrical circuits including these contacts A1 to As, all that is necessary is that one or several of the electrodes should be covered by the alluviation deposit, of which the variation in length, thickness or slope is a function of the variation in the nature or volume of the material to be treated, thus utilizing the conducting properties of the water and of the material forming the alluviation deposit to effect the electrical connection between the electrodes and the bottom of the chute which is included in the various electrical circuits referred to.

These various electrical circuits include an electro-mechanical device of a known type acting on the slide of the evacuator I to open, to reduce or to close the discharge orifice of this device.

In known manner, the electrical currents flowing through the various contacts fixed on the side wall of a chute act for the individual regulation in variable degree of the discharge orifice of one of the extractors provided on this chute and in this invention, the current passing in each of the electric circuits of one or more contacts of one of the washing chutes causes opening of one or several orifices of the evacuator devices provided, either on this chute, or on one or on several of the chutes forming part of the plant.

The plurality of the contacts and of the electrically actuated evacuators ensure a perfect progressiveness in the extraction of the dense materials contained in the ore under treatment.

For example, when the alluviation deposit in the first washing chute has a profile d-e, only a certain number of extractor devices on each of the various washing chutes discharge.

If the profile of the alluviation deposit changes from d-e to a-e, the electrode A1 is covered and closes certain electrical circuits so that certain of the evacuators provided on the first, the second and possibly the third chutes are opened insuch as way as to cope, in the first washing chute, with the increase in the deposit of dense materials by a greater discharge of the dense materials, and, in the lower chutes, in such a way as to draw off the additional dense materials supplied to each of these washing chutes by effecting additional discharge from the first washing chute.

If a larger quantity of dense materials in the mineral to be treated are introduced and the alluviation deposit is profiled on other lines, such as b-e, ce and so on, new electrodes are covered and new evacuators on the various chutes are opened to secure a larger discharge.

The electrical circuit causing the operation described above may be of a very simple nature as shown in Figure 3. The coils X, Y, and Z each represent an electro-magnet as shown at [5 in Figure 2. The coils X1, X2, Y1, Y2 etc. are associated with the evacuators X1, X2, Y1, Y2, etc. respectively as shown in Figure l.

A. source of power 2| is connected to the coils through the conductors shown. Groups of coils are connected in parallel to one side of the power source and to their respective electrodes A which are mounted on the chutes 6 and insulated therefrom by insulators 22. The other part of the circuit comprises the chute 6 which is connected to ground or the other side of the power source.

When the alluvial, which in contact with the chute, reaches electrode A1, a circuit is closed energizing electro-magnets X1 and X2. These electro-magnets, in turn, cause their respective evacuators to open. The process is repeated as successive electrodes are covered with alluvial. thereby opening additional evacuators in all of the chutes.

The manner of connecting the evacuators is subject to great variation as to the number and position of the evacuators which will open when a given electrode is covered; however, it is to be understood that the variations can be made without departing from the scope of my invention.

The increased discharges from the first washing chute have clearly the tendency and effect of bringing back the profile of the alluviation deposit in this chute to a reduced length and thickness so that certain electrical contacts open and the evacuators close, the working of which is regulated by these contacts.

By the automatic control of the regulation of opening and of closing of a certain number of evacuators, it is thus possible to control the alluviation deposit in such a manner that its origin is usually maintained, for example, between the profile lines a-e and be and oscillates by the fluctuations in the supply of dense materials outside this zone.

The alluviation deposits the chutes which follow are also subjected to fluctuations in their characteristics according to the number and output of the evacuators feeding these chutes and drawing off from these same chutes, and contacts A5 to A8 are arranged for the control of said following chutes, but it will be clear that the function of these contacts A5 to As is complementary to that of the first contacts A1 to A4. In this invention, the object of the contacts is to maintain control of the extraction of dense materials in the chutes to which they are applied, the quantity of dense material being governed by that of the alluviation deposit in the first washing chute. This maintenance of the evacuation output in these chutes is fully justified when the alluviation deposit in the first chute is reduced in size, while the deposit in the chute or chutes corresponding to the contacts A5 and As has not yet been subjected to the required amount of reduction.

The temporary maintenance of this extraction leads to a desirable reduction in size of the alluviation deposit in this chute or these chutes and favors a more rapid final elimination of completely graded dense materials, while at the same time, it prevents the return into the washing circuit of too large a quantity of imperfectly purified product.

Before describing broadly the operation of the apparatus according to the present invention, a few facts about the minerals, particularly coal, to be separated should be understood. Clean coal has a variable specific gravity according to its origin or particular characteristics. Bituminous coal, for instance, shows a low specific gravity variable between 1.2 and 1.4. Anthracite coal usually shows a higher specific gravity, around 1.5 to 1.6 or 1.7. Clean coal is accompanied by poor coal with mineral matter occlusions in various proportions, and also by pure mineral matter, the specific gravity of which runs usually at about 2.2 out which goes up to 2.8.

The preparation of the coals and minerals by washing with water and extracting the dense materials can be performed in a number of different manners without departing from the scope of the present invention. The operation to be described is merely one example of a desirable process.

As indicated above, the minerals are poured into the receiving end of chute 6 with entraining water. The washing Water carries the lighter material down the chute and is poured off the lower end of the chute. Some water also accompanies the more dense material which is collected in evacuators 1.

As the profile of alluvial rises, certain contacts along the side walls of the chute 6 are covered causing the opening of certain of the evacuators as described above. The opening of the evacuators causes the dense material to drop down from the upper chute into one of the lower chutes. This dense material passing through has with it some light material which was not poured off the end of the first chute. Thus, in the second chute and also any of the lower chutes, separation of the light from the dense material is continued. A rise in the profile of the alluvial in the lower chutes also causes the evacuators in those chutes to open in accordance with the circuits shown in Figure 3.

After the heavy material has pas ed through the last troughs, it may be found desirable to recirculate the material. The dense material collected at the mouth of the lower troughs is conducted to a cistern where a bucket elevator separates it from the accompanying water. The material is raised again to the receiving end of the top chute for retreatment with normal feed.

In a general manner, while there has, in the above description, been disclosed what is deemed to be a practical and efficient embodiment of the invention, it should be well understood that the application is not to be limited thereto as there might be changes in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claim.

In a plant for the mechanical preparation of coals and minerals by Washing with water and extracting the dense materials; a plurality of downwardly sloping chutes positioned in spaced relation one above the other for receiving wet material made up of the material to be washed and the washing water, the lower chutes receiving wet material from the chute above; a plurality of evacuators positioned longitudinally in spaced relation along the bottoms of said chutes for discharging the heavy products, each of said evacuators including a fixed member mounted to the exit end of said evacuator and a slidable member mounted to said exit end, said two members having inclined facing surfaces converging downwardly forming when separated an orifice having the shape of a truncated cone; electromagnetically operated means operably connected to said slidable member for actuating individual evacuators; a plurality of circuit closing means each associated with a portion of said evacuator actuating means, a portion of said circuit closing means including electrodes spaced longitudinally along the uppermost chute for contact with wet material in said chute as the level of the wet material reaches the various electrodes and effects energization of the respective evacuator actuating means to lower the level of said wet material whereby, as the level of the wet material in said uppermost chute rises, a progressively greater number of electrodes are contacted and a progressively greater number of evacuators are actuated in predetermined groups in at least two of said chutes to control the level of the wet material in said last mentioned chutes; and the remainder of said circuit closing means further including electrodes spaced longitudinally along each of the lower chutes for effecting the actuating of an increasingly greater number of the evacuators of the lower chutes as the level of the wet material in the lower chutes grows increasingly higher.

ADOLPHE DE'I'IENNE, Executor of the estate 0 Antoine France,

deceased.

References Cited in the file of this patent UNITED STATES PA'IENTS Number Name Date 1,508,176 France Sept. 9, 1924 FOREIGN PATENTS Number Country Date 269,017 Great Britain Apr. 14, 1927 456,443 Great Britain Nov. 4, 1936 

